Process of separating vegetable fibrous material



Jan. 3, 1928. 1,654,624

' S. D. WELI 'S PROCESS OF'SEPARATING VEGETABLE PIBROUS'IATERIAL Filed m. 10. 1925 Patented 3, 1928.

UNITED STATES SIDNEY I). WIEiLLS, OF QUINCY, ILLINOIS.

raocnss on snranarme VEGETABLE rrnnous MATERIAL.

Application filed Aug'ust'lO, 1925. Serial 80. 49,461.

This invention relates to'the production of fiber suitable for manufacture of paper and pertains particularly to the treatment.

of wood and other vegetable fibrous material by the steps of the partlcular process and within a certain apparatus, both of which,

comprise a part of the present invention.

The process provides for the treatment of softened woody material and which has been converted into a ligno-cellulosic intermediate product by pounding and rubbing such previously prepared material into pulp in a particular way without breaking the fibers and without the reduction to fragments of more than 'an insignificant proportion of the fibers and cells.

The apparatus provides a rotatable drum structure within which the pulp is tumbled, pounded and beaten by interminghng contact with a plurality of rods which extend in parallel relation lengthwise of the axis of the drum and are free to roll and tumble thereinunder the influence of the rotary movement of the drum. With this improved pulping apparatus the length of the fiber is maintained and the fibers are not d1s.- integrated .into the sawdust-like particles commonly produced and observed in processes in which the grinding apparatus includes a rotary abrading element or cutting element.

Especially does'this invention relate to the mechanical phases of fiber producing processes and to theresul'ting fibrous material purposes, obtained from wood as for example after the originalmaterial has been prepared chemically by boiling the same under pressure in the presence of aqueous solutions of caustic soda and sodium sulphide. caustic soda and sulphur, or sodium I sulphite and sodium carbonate of suitable concentration to soften the woody material and to form the lingo-cellulosic intermediate product above mentioned. i a

At the present state of the pulp makers art-the processes used may be divided- 'into two groups, the mechanical and the chemical.

The mechanical process consists essentially of pressing blocks of wood against a revolvi'ng grindstone in the presence of water and the wood is reduced to pulp by grinding and the frictional. heat developed. In this process the action is so severe that comparaover fifty per cent of thewood substance is suitable for paper manufacture and for other tively few of the fibers survive in their entity and a large'portion of the-pulp consists of fragments of single fibers or of bundles of fibers. -In the chemical processes the wood is cut to chips and digested under pressure in aqueous solutions ofthe bisulphiteis of 'thealkaline earths, and, sulphurous acid or caustic soda or caustic soda and sodium sulphide or sodium sulphite. The digestion is carried to such a point that dissolved and a product testing over'.90% cellulose is left. In these processes the ultimate fibers are intact, but the bond between them has been removed so that th'ey-separate with the slightest mechanical agitation. By ultimate fiber is meant the elongated cells which are attached longitudinally and cemented together radially by incrusting matter consisting largely of lignin and hemicelluloses. Their entity is readily-discernible underthe microscope and their length is approximately 100 times or more their diameter.

' In the present improvement the wood is also cut to chips and the chips subjected to aqueous solutions of suitable chemicals at. elevated temperatures after first being sub- -.jected to an impregnation treatment under pressure. The digestion however is on] carried to the point that the middle lamella or cementing material between the fibers is softened, but not completely dissolved. The softened chips are then capable of reduction to their ultimate fibers and cells by suitable pounding or rubbing or a combination of both in accordance with the present invention. A pulpis obtained that has the general appearance oi pulp obtained by ,the chemical processes mentioned, but instead of a yield of from 40 to 50 per c ntvbeing obtained, a yield of from 60 to8 per cent is realized, depending on-the species of wood. and the severity of the treatment. While these pulpsare similar in appearance to what are'generally known as chemical ulps they have distinct chemical characteristics, 1 as will be shown in the following table of analysis. In this table the terms used may be explained as follows: 7 Solubility in .1 sodium hydrowide.- This test is the amount of material dissolved on treatment of the pulp one hour in. a 1% solution-of sodium hydroiide at C.

ments; with chlorine gas in the presence of water and washing with sodium sulphite solutions under the conditions suggested by Cross .and Bevan and. described b hem. 9,

Schorger Jour. Ind. and Eng.

(1917) 556. In accordance with this, the

following procedure is used. Two grams of air dry pulp in an alundum crucible are extracted three to four hours with a mixture of 67 per cent of benzol and 33 per cent alcohol. After evaporation of the solvent the shavin' s are thoroughly washed with hot water using the suction pump. The moist pulp is then transferred with a pointed glass rod to a 250 cc. beaker, evenly distributed over the bottom, and subjected to a stream (about forty bubbles per minute for each sample) of water washed chlorine gas for half an hour.

5 sure uniformity of chlorination. After the I chlorine treatment the pulp is treated with a.

0 again returned with the glass rod to the The end of the tube delivering the chlorine gas should be about one-half inch above the pulp. At intervals ofsix to seven minutes the contents of the beaker are stirred to insolution of SO until the chlorine odor disappears, transferred to the alundum crucible, and washed with hot water. The pulp is beaker. and 100 cc. of a two per cent sodium sulphite solution are added and the beaker,

covered with a watch glass, placed in aboiling water bath for minutes. The fibers 5 are then transferred to the crucible and Two to four grams of air dry pulp are washed with water. The aboveprocedure is seldom sufficient to remove all the lignin, so

that the treatment with chlorine and subsequent treatment as outlined above is repeated until the fibers are practically a uniform white. -The second and following treatments 5 with chlorine should not be longer than 15 v to 30 minutes. After all the lignin has been removed the fibers are given a final bleaching by adding 20 cc. of a 0.1 per cent solution of potassium permanganate, allowed to stand 10 minutes and rendered colorless with SO solution. a The fibers are then thoroughly washed with hot water, dilute acetic acid, then with hot water, then with alcohol and finally with ether, and, dried for two hours at 105 Gain the air oven. After cooling by a desiccator over H 80 the crucible is weighed in a weighing bottle.

Lz'gmin.-This-result consists of the residue left after treatment with sulphuric acid under conditions prescribed by 0st and Wilkening and reportedby Gross and Bevan in Researches on Cellulose, III, 39, (1906- 10). In adapting that method to the resent problems the followingsteps are fo lowed.

weighed in anlflundum thimble, extracted "with ether in a oiglet apparatus for 3 to 4.

hours, and dried at 105 C. The pulp is then removed from the alundum extraction thimbles, placed in-250 cc. beakers, divided into fine partlcles and treated with 40 cc. of 72.0

per cent sulphuric acid. The hydrolysis is allowed to proceed for 16 hours at room temperature, with frequent stirring at the beginning of the operation. The resulting solution is transferred we two liter Erlenmeyer flask diluted to 1570 cc. with distilled water, which makes the concentration of Cellu- Material analyzed I rose Llgniw Per rent Loblolly pine; Jack pine Mechanical ulp: Spruc Very raw su phite pulp: Spruce. Standard sulphite pulp: Spruee. Soda pulp:

pruce Jack pine i Loblolly pine Aspen Sulphate pulp:

Spruce Jack pine Loblolly pine ngleaf pine 'Ligno-eellulosic material, strongly alkaline reagents:

Aspen (soda liquor) Loblollypine (soda liquor). J aek pine (soda liquor) Jack pine (sulphate liquor) Ligno-eellulosie material, neutral or slightly alkaline reagents:

a is

Jack pine: Loblolly pine Tamarack.

,The ligno-cellulosic materialmay be differentiated from mechanical pulps in that, they contain less than 10% of substances soluble in 1% caustic soda solution and 80% or more of the fibers retain 50% or more'pf their ultimate fiber length. It may be differentiated from the sulphite pulps of commerce in that when obtained from deciduous wood, they are not more than 9% soluble in 1% caustic soda solution, contain from to 91% cellulose. and from 8% to 23% of lignin. It may be differentiated from the soda or sulphate pulps of commerce in that they -,'contain less than 91% cellulose and more than 8% of lignin. When derived from coniferous species they contain from 63% to of cellulose and from 20% to a2 e lignin and is not more than 7% soluble insodium hydroxide.

The chemical treatment thus far described. is not a part of the present invention but is described and-claimed in the copendi-ng apwith rigid bars or viding the pounding plication filed jointly by the applicant here- In with John D. Rue and Francis G. Rawling, Serial .No. 127,178, filed Aug. 4,1926, and which was predicated on and copied in part from this present application.

An important element of novelty in the present process is the use of mechanical dis integrating types of apparatus in the process which have never before been. used on this sort of material for the purpose. The beaters, refining engines or attrition mills fitted blades which have been usedin the Japer making art have been found to pro uce a very unsatisfactory material when applied to softened woody material. Vascular bundles and fragments of the medulary rays are produced which resist reduction longitudinally and appear in the, sheet of paper formed from the resultant product as granular sawdust like specks or slivers which render it practically useless for the purpose intended. If the grinding is carried on to the point Where these particl eshave been satisfactorily reduced in size the fibers are also reduced in length until they have lost their power of imparting the desired strength to the paper. On the other hand when properly reduced by pounding or rubbing these fragments do not appear in the finished product and a sheet of uniform texture may be obtained. Not only "may this pounding or rubbing action be appliedto softened woody material, but it may be applied with excellent results to the heating of the standard chemical pulp's or rag or rope or jute pulps of commerce. The rod mill has been found most satisfactory this purpose.

The process is carried out with thetuse of particular apparatus which is used for proor rubbing action and which apparatus is identified, as-above mentioned, as a rod mill.

apparatus willbe briefly described by reference to the accompanying sheet of drawings \in which:

Figure 1 represents a top plan view showing an elongated-cylindrical drum which is mounted at either end in suitable supporting bearings, and which is shown as having. adjacent one enda large gear encircling it, the teeth of which are enmeshed with a smaller gear driven from any suitable source of power;

Figure 2 is a vertical longitudinal section along the line 2-2 of Figure 1 illustrating the intake and outlet'openings of the drum and showing the position within the drum ofa plurality of long. rods whicli lie free to for roll and tumble during the rotary movement of the drum; and

Figure?) 15' a sectional view taken on the line 3-3 of Figure 1 vertically and transversely through the drum showing the position of the rods during the revolution of the drum.

The structure of this Referring in detail to the several figures in the drawing, 1 indicates the cylindricallike shell of a rotary drum which is mounted with its longitudinal axis extending substantially horizontally and supported in bearings 2- at either end onupright supports 3. 4 indicates a large annular gear secured to theflange at one end of the drum. In mesh with the teeth of the gear 4 is a smaller gear 4 which is driven by any suitable source of power through a shaft 4? and pulley wheel 4. The intake end 5 receives chips which may ormay not have been previously softened, but preferably this material is softened in accordance 'with the severalsteps outlined in the description hereinafter provided. During the revolution of the drum 1 the material works its way gradually toward the out-- let end and discharges through theopening 6, the rate of discharge being proportional with the rate of intake. A plurality of rods 7 in number sufiicient to half fill the drum lie along'the bottom and on top of each other. These rods are preferably from-one to two inches in diameter an have a -two inches shorter than the inside length of the drum. The inner. lining of the drum may have a contour variable according to the type of fiber to be treated. A so-called wave type shell liner has operated td adu vantage, and in this particular form there are occasional rounded humps which extend lengthwise of the shell or drum wall and aid in lifting the rods and fibrous material from the bottom during the revolution of the length about rods and fibrous'material are lifted upward with the movement of the casing and the entire mass of fibrous material, intermixed with the rods rolls from top to bottom of the pile toward the opposite side of the drum.

This rolling and tumblingimovemen't ofthe rods serves to rub, A iviously softened vegetable fiber material into a relatively open condition, thus providing a satisfactory pulp. It is "obvious-that there is little if any cutting the felting property of the fibers, and itis also obvious that as long as there are any iinreduced bundles or lumps .in the mass, they will receive substantially the entire acpound and beat the preaction detrimental to tion of the rods and correspondingly the reduced will be .will escape furtherefore obvious that portions that are suflicie'ntly protected. by the lumps and ther reduction. It is the rod mill is selective in its action and con sequently attains its results with the least expenditure of energy on material already in proper condition. It is thus also different. of equipment from positively operated types pulp.

The action of the rods in the rod mill on the particles of Vegetable material may be compared to the treatment which the particles would receive on an inclined surface while pounding elements roll from top to bottom across'the inclined surface, rolling,

crushing and pounding the particles as the rods tumble from top to bottom. The pile' of rods maintains more or less a uniform inclined surface, but. as regards the relation of one rod to another, the mass or pile of rods is in constant transition, the rod elements moving from the bottom of the pile toward the crest of the pile, being carried upward by the rotation of the casing, successive rods, after reaching the crest of the pile, being carried so high that the uppermost rod is carried so far that it is no longer retained by the rods next beneath, but falls downward across the inclined surface of the more slowly moving rods until it reaches the side of the pile and comes to rest adjacent the casing on the side thereof opposite to that from whence it started. In the constant transition of individual elements of the pile of rods from bottom to top, and thence more rapidly across the inclined face of the pile of rods, it will be obvious that the respective *rods making up the inclined face also are moving downward, although the largest number of the rods thus forming the' inclined surface move more slowly than the ones which are carried to the extreme crest or top of the pile, and whichtumble across the surface to'the opposite side. It will also be obvious that the plurality of rods composing the inclined surface provide a corru-- gated eflect. Accordingly, particles of vegetable material appearing on the inclined surface of the pile of rods are subjected to the impact of the rapidly moving rods as they are released from the top side and roll across the corrugated surface toward the lower side striking and rolling across the outer side of each of the individual elements thus forming the corrugated surface. It-will also be obviousthat not only will the particles of vegetable material be given a peculiar treatment in between the rods and within the mass of the rods by reason of the constant transitionmovement of the shifting body of rods, but also that an unusual'impact treatment is given to all particles of the vegetable material which lie on the upper surface, and such upper particles receive an impact treatment due to the direct contact of a freely moving, falling, tumbling body.

The following procedure may be used in treating fresh wood fibrous material to produce the ligno-cellulosic material descrlbed. The wood is first converted to chips in the manner used in chemical pulp 'mills and charged into a digester. They are then 1m- 7 ate gave satisfactory static pressure by means of a pump, steam,

air, or any other method known to the art. After impregnation for half an hour or more at 100 pounds pressure the softening solution will be found to have practically penetrated the chips and the excess over that required for softening is removed. Using 10 parts of sodium sulphite and 4 parts of sodium bicarbonate per 100 parts dry weight of gum chips gave excellent results. The

substitution of sodium carbonate for bicarbonate was also satisfactory. The substitution of 2 parts caustic soda for the bicarbonresults with loblolly pine. greater strength is desired 8 parts of caustic soda and one part of sulphur was satisfactory. 8% calcium bisulphite and 2% sulphurous acid gave good results with tamarack. It can thus be seen that a wide range of chemicals may be used. This impregnat1on feature is important because it makes possiblethe softening of thewoo'd uniformly through its thickness. ,By the term unifornii is meant the even softening to substantially the same degree from the extenor to the center of each piece of wood. Thus, the chips after treatment are practically as soft at their centers as they are on the outslde. Without previous impregnation and with the use of the direct cook only, the woody material is likely to become damaged by over cooking on the exterior portions before the interior is adequately s0ftened. Thus, with ordinary cooking methods, the undigested chips will be almost completely cooked on the outside, and in extreme cases, the center wilhbe bright wood, not

For pulpsfrom the pines where i even discolored by the cooking liquor. Ac-

cordingly, in view of-the fact that the par- I ,ticular subsequent mechanical separation of suffici'ent in the fourth, and six hours coming up to a temperature of 120 C. was sufficient in the last. I The contents are then removed from the digester and reduced to ultimate fibers bypassing through the rod mill of the present invention. The pulps produced are then washed and prepared 1n suitable form by the customary steps, used in the art. In the use of rubbing and pounding devices'screens are desirable to allow the ultimate fibers or cells to pass on and return the material insufliciently disintegrated for .additional rubbing and pounding thereby or pounded by adinittinghot water or blowing steam into the mill to maintain an elevated temperature and at the same time ad mit sodium carbonate, milk of lime or any of the known agents or mixtures thereof with the raw ber.

Not only is the rod mill treatment suit-' able for rubbing apart the fibers insoftened fibrous material or for both softening and rubbing where the material is to be used for papenmanufact'ure in the'unbleached and unpurified condition, but it may be used where the product therefrom is to be further purified by washing, treatment with chlorine gas or chlorine water, boiled with sodium sulphite, sodium carbonate, sodium h droxide or some similar compound capa le of dissolving the products of chlorination. .The fibrous product may then be subjected to a' repetition of the same treatmentandthen bleached by customary methods or. when notmecessary there etition of the chlorination treatment may omitted. The purificat on processes outlined above are not claimed except in so far as the rod mill is used t o prepare the material into proper condition without which ,these processes are unsatisfactory. The use of the rod mill in preparing lime cooked straw for paper products or for further. urification by means of ahrlgrmation netho is particularly impor- Should a mixture of coniferous and deciduous material be treated inv accordance with the process of this invention, the 'resultant ligno-cellulosic .pulped material would have varying proportions of lignin and cellulose in its content ranging from 8 per cent to 32 per cent of and from 63 per cent to 91 per cent 0 cellulose, depending on the ratio of coniferous and deciduous material present.

I claim 1 a 1. In the production of fibers from ve table material for use in making paper, a method of treating material which has been uniformly softened but not pulped, which 4 method consists in separating the fibers of as between parallel pounding. surfaces of a plusaid softened material by pounding the same rality of elon ated extend in su stantial constant parallel relation and which freely fall in intermingled contact with the material and impact" upon particles of the material.

2. In the production of fibers from vegetable material for use in making paper, the method of treating material which has been cooked with chemicals until the middle lamellais softened and which cook has been terminated before the middle lamellais completely dissolved, which method consists in rial by pounding the same between parallel pounding surfaces of a pile of rods which substantially constantly extend parallel to each other and are tumbled with the material and which fall with the material and impact u on particles of the material, wherelby't e length of the fibers is maintaine 3. In the production of fibers from'vege-' pounding elements which separating the fibers of said softened mate-- table material for use in making paper the methbd of-treating material which has eeii softened but not pulped, which method con-'- 0 sists in subjecting the vegetable fibrous material to a mechanical treatment in which the chemically treated fibrous material which has been softened is commingled with a pile of loose pounding elements comprising parallel rods extending substantially constantly and substantially horizontally and the commingled mass is tumbled in a rotary drum mounted to turn on an axis parallel to the length of the iods whereby the previously softened fibers ai'e pounded between falling parallel surfaces and the fibers are separated from each other. -v 4. In the production of fibers from vegetable material for use in making paper, the method of treating vegetable particles to loosen the fibers thereof which method consists in pounding particles of the fibrous ma terial between parallel pounding surfaces of a plurality of elongated pounding elements which extend in substantially constantly parallel relation and which freely fall in intermingled contact with the fibrous material and within a restricted zone and impact on particles of the material. 5. In the production of fibers from vegetable material the method of treating vegetable particles to loosen the fibers thereof which method consists in subjecting the fibrous material in a drum mill having freely tumbling disintegrating rods therein to a tumbling action in intermingled contact -with said rods while the drum mill is rotated on an axis parallel to the axis of the rods whereby the mass'of rods and fibrous material is lifted-and permitted to tumble downwardly from that side of the interior of the drum on which it is lifted.

6. 111 the production of pager pulp from vegetable material, the met 0 of pounding upper surface of a apart fibre bundles which method comprises ,ing from the upper side of the pile toward subjecting particles of the vegetable material to a crushing treatment on the inclined pile of elongated pounding elements arranged with their longest axes substantially parallel to each other and horizontal and between said surface and a number of rapidly moving like elements falling from the upper side of the pile to- .ward the lower side, and constantly moving elements from the lower side of the pile to the upper side'and constantly releasing elements at the upper side to roll downward across the particles of vegetable material on said inclined surface. 7. In the production of paper pulp from vegetable materiahthe method of pounding apart fibre bundles which method comprises subjecting particles of the vegetablematerial to a crushing treatment on the inclined upper surface of a pile of elongated pound ing elements arranged with their longest axes substantially parallel to each other and horizontal and between said surface and a number of rapidly moving like elements falling from the upper side of the pile toward the lower side, and constantly moving elements from the lower side of the pile to the upper side and constantly releasing elements at the upper side to roll downward across the particles of vegetable material on said inclined surface, the plurality of elements of said inclined surface-constitutin a corrugated surface on which the vegeta le particles are pounded.

8. In the production of paper pulp from vegetable material, the method of pounding apart fibre bundles which method comprises subjecting articles of the vegetable material to a crus ling treatment on the inclined upper surface of'a pile of elongated pounding elements arranged with their long- I est axes substantially parallel to each other and horizontal and between said surface and a number of rapidly moving like elements falling from the upper side of the pile toward the lower side, said pile bein in con- 7 stant transition during conduct of t e method and in which transition elements from the lower part of the .pile are moved on the side opposite to said inclined surface upwardly to the crest of the pile, thence, to tumble downwardly to impact on the vegetable particles, remaining constantly parallel throughout the movement.

9. In the production of aper pulp from vegetable material, the nietliod of pounding apart fibre bundles which method comprises subjecting particles of the vegetable material to acrushing treatment on the inclined upper-surface of a pile of elongated ounding elements arranged with their on'gest axes substantially parallel to each other and horizontal and between said surface and a number of rapidly moving like elements fall- 10. In the production of I products from fi s aterials, the method of beating P ng the fibers be.

which consists of tween parallel pounding surfaces of a lurality of elongated pounding elements w 'ch extend in substantially constantly parallel relation and which freely fall in mtermingled contact with the fibrous material and within a restricted zone and impact on particles of the material. y

11. In the production of products from .fibrous materials, the method of beating which consists in subjecting the fibers in a drum mill having freely tumbling disintegrating rods therein to a tumbling action in intermingled contact with said rods while the drum mill is rotated on an axis parallel to the axis of the rods whereby the mass of rods and fibrous material is lifted and permitted to tumble downwardly fromthat side of the interior of the drum on which it is lifted. I

12. In the production of products from fibrous materials, the method of beating which consists of subjecting the fibers to a crushing treatment on the inclined upper surface of a pile of elongated pounding elements arranged with their longest axes substantially parallel to each other and horizontaland between said surface and a number of rapidly moving like elements falling from the upper side of lower side, and constantly moving elements from the lower side of the pile to the upper side and constantly releasing elements at the upper side to roll downward across the particles of fibrous material 13. In the fibrous materials, the method of beating which consists of subjecting the fibers to a crushing treatment on the inclined upper surface of a pile of elon ated pounding elements arranged with their longest axes substantially parallel to each other and horizontal and between said surface and a number of rapidly moving like elements fallin from the upper side of thepile toward the lower side, and constantly moving elements from the lower side of the pile to the upper I side and constantlyreleasing elements at the surface, the plurality ofelements of saidinclined surface constituting acorrugated 5 surface on which .the fibrous particles are pounded.

14. In the production of products from fibrous materials, the method of beating which consists of subjecting the fibers to a 1 crushing treatment on the inclined upper surface of a pile of elongated pounding elements arranged with their longest axes substantially arallel to each other and horizontal and etween said surface and a numher of rapidly "moving like elements falling from the upper side of the pile toward the lower side, said pile being in constant transi-' tionduring conduct of the method and in which transition elements from the lower part of the file are moved on the side opposite to sai inclined surface upwardly to the .crest/ of the pile, thence, to tumble downwardly to impact on the fibrous particles, remaining constantly parallel throughout the movement.

ture.

.Intestimony wl 1ereof I aifix 'my signa- 

